Differential compression bone screw

ABSTRACT

A differential compression bone screw and a method are provided for compressing adjacent bone portions together to encourage bone fusion. The compression bone screw is comprised of a head portion and a shank. A center hole extends from the head portion to a distal end of the shank. A superior end of the head portion includes a shaped opening that receives a tool for driving the compression bone screw into a hole drilled in a patient&#39;s bone. An inferior end of the head portion includes barbs that engage with surrounding bone tissue. A smooth portion of the shank is disposed between proximal threads and distal threads that rotatably engage within the hole in the patient&#39;s bone. A thread pitch of the distal threads is greater than a thread pitch of the proximal threads, such that the compression bone screw comprises a differential pitch configured to compress the adjacent bone portions.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.16/422,141 filed on May 24, 2019 and U.S. patent application Ser. No.15/612,520, filed Jun. 2, 2017, now issued as U.S. Pat. No. 10,349,992which claims the benefit of and priority to U.S. Provisional ApplicationNo. 62/344,823, filed Jun. 2, 2016, both entitled “DifferentialCompression Bone Screw”, the entirety of which are incorporated hereinby reference.

FIELD

The field of the present disclosure generally relates to securing bonestogether. More particularly, the field of the present disclosure relatesto bone screws and methods for repairing bones of a patient.

BACKGROUND

A fusion bone plate implant may be utilized in conjunction with one ormore fasteners so as to generate compression and stability at a boneinterface. An implant coupled with fasteners generally serves tostabilize bones, or bone parts, relative to one another so as to promotebone fusion. In many applications, bone plates and fasteners are used tofuse bones, or bone parts, of the human body, such as bones in the foot,the ankle, the hand, the wrist, as well as various other portions of thebody. Furthermore, during the course of certain medical procedures, asurgeon may immobilize one or more bones or the bone fragments bystabilizing the bones together in a configuration which approximates thenatural anatomy. To this end, the surgeon may use fasteners to attachthe bones to a bone plate implant so as to hold the bones in alignmentwith one another while they fuse together.

In some instances, however, a bone plate may be impractical forimplantation in a portion of the body that requires treatment. What isneeded, therefore, is a compression bone screw that is configured tofuse bones in absence of a fusion bone plate.

SUMMARY

A compression bone screw and a method are provided for compressingadjacent bone portions together. The compression bone screw is comprisedof a head portion that includes a superior end and an inferior end. Ashank extends distally from the inferior end to a distal end. Proximalthreads and distal threads are disposed along the shank and areconfigured to rotatably engage within a hole drilled in a patient'sbone. The proximal threads are comprised of a first thread pitch and thedistal threads are comprised of a second thread pitch, such that theshank comprises a differential pitch. The second thread pitch is greaterthan the first thread pitch, such that engaging the screw within thehole causes the distal threads to push a first bone portion toward asecond bone portion near the proximal threads, thereby closing afracture between the first and second bone portions. Intermediatethreads may be disposed between the distal and proximal threads andcomprise a thread pitch that decreases from the second thread pitch nearthe distal threads to the first thread pitch near the proximal threads.

In an exemplary embodiment, a compression bone screw for compressingadjacent bone portions together comprises a head portion comprised of asuperior end and an inferior end; a shank extending distally from theinferior end to a distal end; and proximal threads and distal threadsdisposed along the shank, the proximal threads comprised of a firstthread pitch and the distal threads comprised of a second thread pitch,such that the shank comprises a differential pitch. In another exemplaryembodiment, intermediate threads are disposed between the distal threadsand the proximal threads and comprise a thread pitch that decreases fromthe second thread pitch near the distal threads to the first threadpitch near the proximal threads.

In another exemplary embodiment, a center hole extends from the headportion to the distal end and is configured to receive any of variousguidewires, trocars, and other similar instruments configured to directthe compression bone screw to a target opening of a hole drilled in abone. In another exemplary embodiment, the superior end includes ashaped opening that is substantially concentric with the head portionand configured to engagedly receive a tool for driving the compressionbone screw into the hole drilled in the bone, and wherein the inferiorend comprises a plurality of barbs disposed around the circumference ofthe inferior end and configured to fixedly engage with surrounding bonetissue. In another exemplary embodiment, the inferior end is configuredto engage within an opening of the hole drilled in the bone, such thatthe superior end countersinks below the exterior surface of the bone. Inanother exemplary embodiment, the inferior end is configured to engagewithin an opening of a bone fusion plate, such that the superior endcountersinks within the opening and the inferior end presses the bonefusion plate against the surface of the bone.

In another exemplary embodiment, the distal threads and the proximalthreads are configured to rotatably engage within a hole drilled in abone, such that the compression bone screw advances into the hole uponbeing turned by way of a suitable tool. In another exemplary embodiment,the proximal threads comprise a first diameter, the distal threadscomprise a second diameter, and a smooth portion disposed between theproximal threads and the distal threads is comprised of a diameter thatis less than the first diameter and the second diameter, and wherein thefirst diameter is greater than the second diameter. In another exemplaryembodiment, a tapered diameter extends from the second diameter to arounded portion comprising the distal end, the rounded portion and thetapered diameter being configured to minimize resistance to forwardmovement of the compression bone screw advancing within the interior ofa hole drilled in a bone. In another exemplary embodiment, one or moreflutes are disposed along the tapered diameter and comprised of at leastone cutting edge configured to clean the interior of a hole drilled in abone during advancing of the compression bone screw within the hole.

In another exemplary embodiment, the second thread pitch is greater thanthe first thread pitch, such that the distal threads push a first boneportion toward a second bone portion near the proximal threads, therebyclosing a fracture between the first bone portion and the second boneportion. In another exemplary embodiment, a smooth portion disposedbetween the proximal threads and distal threads is configured to allowthe fracture to close as the first bone portion and the second boneportion are compressed together. In another exemplary embodiment, thesecond thread pitch ranges between substantially 1-3 times greater thanthe first thread pitch. In another exemplary embodiment, the secondthread pitch is substantially 2-times greater than the first threadpitch. In another exemplary embodiment, intermediate threads aredisposed between the distal threads and the proximal threads, theintermediate threads having a thread pitch that decreases from thesecond thread pitch near the distal threads to the first thread pitchnear the proximal threads.

In an exemplary embodiment, a method for a differential compression bonescrew comprises forming a head portion comprised of a superior end andan inferior end; orienting a shank distally from the inferior end; andconfiguring a differential thread pitch along the shank. In anotherexemplary embodiment, configuring the differential thread pitchcomprises configuring proximal threads having a first thread pitch andconfiguring distal threads having a second thread pitch, such that thesecond thread pitch is greater than the first thread pitch. In anotherexemplary embodiment, configuring the differential thread pitch furthercomprises disposing intermediate threads between the distal threads andthe proximal threads, the intermediate threads having a thread pitchthat decreases from the second thread pitch near the distal threads tothe first thread pitch near the proximal threads. In another exemplaryembodiment, configuring the differential thread pitch further comprisesforming a smooth portion of the shank disposed between the proximalthreads and the distal threads. In another exemplary embodiment,orienting the shank further comprises extending a center hole from thehead portion to a distal end of the shank and surrounding the centerhole with a shaped opening in the superior end. In another exemplaryembodiment, forming the head portion further comprises configuring aplurality of barbs disposed around the circumference of the inferior endso as to fixedly engage with surrounding bone tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings refer to embodiments of the present disclosure in which:

FIG. 1 illustrates an isometric view of a distal portion of an exemplaryembodiment of a compression bone screw that may be used for repairingbones of a patient;

FIG. 2 illustrates an isometric view of a proximal portion of anexemplary embodiment of a compression bone screw that may be used forrepairing bones of a patient;

FIG. 3 illustrates a side view of an exemplary embodiment of acompression bone screw that may be used for repairing bones of apatient;

FIG. 4 illustrates a side view of the exemplary embodiment of thecompression bone screw of FIG. 3, showing exterior diameters along ashank of the compression bone screw;

FIG. 5 illustrates an exemplary use environment wherein an exemplaryembodiment of a differential compression bone screw is longitudinallydisposed within substantially the center of a repaired bone;

FIG. 6 illustrates an isometric view of a proximal portion of anexemplary embodiment of a compression bone screw that may be used forrepairing bones of a patient; and

FIG. 7 illustrates a side view of the exemplary embodiment of thecompression bone screw of FIG. 6, showing a differential thread pitchdisposed along a shank of the compression bone screw.

While the present disclosure is subject to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and will herein be described in detail. Theinvention should be understood to not be limited to the particular formsdisclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the present disclosure.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present disclosure. Itwill be apparent, however, to one of ordinary skill in the art that theinvention disclosed herein may be practiced without these specificdetails. In other instances, specific numeric references such as “firstscrew,” may be made. However, the specific numeric reference should notbe interpreted as a literal sequential order but rather interpreted thatthe “first screw” is different than a “second screw.” Thus, the specificdetails set forth are merely exemplary. The specific details may bevaried from and still be contemplated to be within the spirit and scopeof the present disclosure. The term “coupled” is defined as meaningconnected either directly to the component or indirectly to thecomponent through another component. Further, as used herein, the terms“about,” “approximately,” or “substantially” for any numerical values orranges indicate a suitable dimensional tolerance that allows the part orcollection of components to function for its intended purpose asdescribed herein.

In general, the present disclosure describes an apparatus and a methodfor a differential compression bone screw for compressing two adjacentbone portions together, including compressing bone fractures, fixatingosteotomies, and joining fusions. The compression bone screw iscomprised of a head portion and a distally extending shank. A centerhole extends from the head portion to a distal end of the shank. Thehead portion is comprised of a superior end and an inferior end. Thesuperior end includes a shaped opening that is substantially concentricwith the center hole and configured to engagedly receive a tool fordriving the compression bone screw into a hole drilled in a patient'sbone. The inferior end includes a plurality of barbs that are disposedaround the circumference of the inferior end and are configured tofixedly engage with surrounding bone tissue. Proximal threads and distalthreads are disposed on the shank and configured to rotatably engagewithin the hole in the patient's bone, such that the compression bonescrew advances into the hole upon being turned by way of the tool. Athread pitch of the distal threads preferably is greater than a threadpitch of the proximal threads, such that the compression bone screwcomprises a differential pitch configured to compress the two adjacentbone portions, thereby closing a fracture there between.

FIGS. 1-4 illustrate an exemplary embodiment of a compression bone screw100 that may be used for repairing bone fractures, fixating osteotomies,joining fusions of the skeletal system, and the like. It should beunderstood that the terms “bone screw,” “fastener,” “fixator,” “elongatemember,” and “screw” may be used interchangeably herein as theyessentially describe the same type of device. The compression bone screw100 generally is an elongate member comprised of a head portion 104 anda shank 108. As best shown in FIGS. 1-2, a cannulation or center hole112 extends longitudinally from the head portion 104 to a distal end 116of the shank 108. The center hole 112 is configured to receive any ofvarious guidewires, trocars, and other similar instruments for directingthe bone screw to a hole drilled in the patient's bone.

The head portion 104 is comprised of a superior end 120 and an inferiorend 124. As best illustrated in FIG. 2, the superior end 120 may includea shaped opening 128 that is substantially concentric with the centerhole 112. The shaped opening 128 generally is configured to engagedlyreceive a tool suitable for driving the bone screw 100 into the holedrilled in the patient's bone. Although in the illustrated embodiment,the shaped opening 128 is comprised of a hexalobe shape, any of variousmulti-lobe shapes, as well as other polygonal shapes, are alsocontemplated.

The inferior end 124 preferably is configured to countersink within thehole in the bone. Thus, the superior end 120 is not left protrudingabove the exterior surface of the bone once the compression bone screw100 is fully engaged with the patient's bone. Further, a plurality ofbarbs 132 disposed around the circumference of the inferior end 124 areconfigured to engage with the surrounding bone tissue so as to preventthe bone screw from backing out of the hole in the patient's bone. Insome embodiments, however, the inferior end 124 may be configured to bereceived within an opening of a bone fusion plate, such that thesuperior end 120 countersinks within the opening of the bone fusionplate and presses the plate against the surface of the patient's bone.

As best shown in FIGS. 3-4, the shank 108 is comprised of proximalthreads 136 and distal threads 140 that share an intervening smoothportion 144. The proximal threads 136 have a diameter 138, and thedistal threads 140 have a diameter 142. A tapered diameter 148 extendsfrom the distal threads 140 to a rounded portion 152 that comprises thedistal end 116. The smooth portion 144 is comprised of a diameter 146that is less than the diameters 138 and 142 so as to facilitate passingthe smooth portion 144 through the bone with relatively littleresistance. Further, in the illustrated embodiment, the threads 136 and140 share substantially similar exterior diameters, 138 and 142,respectively, as shown in FIG. 4. In some embodiments, however, thediameter 138 of the proximal threads 136 may be greater than thediameter 142 of the distal threads 140. Various diameters of theproximal threads 136 and the distal threads 140, as well as the diameter146, are contemplated, without limitation.

The threads 136 and 140 are configured to rotatably engage within asuitably sized hole drilled in the patient's bone. Thus, turning thebone screw 100 in an appropriate direction by way of a tool coupled withthe shaped opening 128, drives the distal threads 140 to engage withbone tissue surrounding the hole, and thus advancing the bone screw 100deeper into the hole in the bone. The proximal threads 136 engage thebone once a majority of the bone screw 100 is already disposed withinthe hole in the bone. Continued turning of the bone screw 100 thencountersinks the inferior end 124 into an upper-most portion of the holein the bone, and draws the superior end 120 beneath the exterior surfaceof the patient's bone.

Moreover, the illustrated embodiment of the compression bone screw 100comprises a differential pitch wherein the distal threads 140 have athread pitch that is greater than the thread pitch of the proximalthreads 136. In operation, the greater thread pitch of the distalthreads 140 pushes the bone portion near the distal threads toward thebone portion near the proximal threads 136. The diameter 146 of thesmooth portion 144 allows the fracture to close as the bone portions arecompressed together. In some embodiments, the thread pitch of the distalthreads 140 may range between substantially 1-3 times greater than thethread pitch of the proximal threads 136. Preferably, however, thethread pitch of the distal threads 140 is substantially 2-times greaterthan the thread pitch of the proximal threads 136. A wide variety ofdifferential pitch configurations are contemplated within the scope ofthe present disclosure.

It is contemplated that the differential pitch of the compression bonescrew 100 is particularly well suited for compressing bone fractures,fixating osteotomies, joining fusions, as well as any other surgicalprocedure wherein compressing two adjacent bone portions is desired,without limitation. It is further contemplated that the compression bonescrew 100 may be advantageously oriented longitudinally with respect toa patient's bone. FIG. 5 illustrates an exemplary use environment 156wherein the compression bone screw 100 is longitudinally disposed withinsubstantially the center of a repaired bone 160. The proximal threads136 and the distal threads 140 are engaged with healthy bone tissue,while a repaired fracture 164 is disposed along the smooth portion 144.Further, the head portion 104 is countersunk within an entry hole 168that was drilled into the repaired bone 160 by a surgeon. As will beappreciated, the compression bone screw 100 may be implemented in any ofvarious lengths and diameters so as to advantageously repair a widevariety of differently sized and shaped bones within the human body.Furthermore, it is envisioned that the compression bone screw 100 may beconfigured for use in a veterinary capacity, and thus the bone screw 100may be implemented with various shapes and sizes that are suitable foruse in different types of animals.

As will be appreciated, the rounded portion 152 and the tapered diameter148 are configured to minimize resistance to forward movement of thecompression bone screw 100 advancing within the interior of a bone hole.As best shown in FIG. 1, the distal end 116 and the tapered diameter 148of the bone screw 100 are further comprised of one or more flutes 172that extend from adjacent of the center hole 112 and spiral along thetapered diameter 148. A pair of cutting edges 176 borders each of theflutes 172. Although the illustrated embodiment of the bone screw 100comprises three flutes 172, and thus six cutting edges 176, more than orless than three flutes 172 and six cutting edges 176 may be incorporatedinto different implementations of the bone screw 100 without limitation.As will be appreciated, the cutting edges 176 advantageously clean theinterior of the bone hole and increase the diameter of the hole toaccept the distal threads 140 of the advancing bone screw 100. As willbe appreciated, the spiral, or a rate of twist, of the flutes 172generally controls the rate of bone debris removal from the interior ofthe bone hole during rotation of the bone screw 100. It is contemplatedthat the flutes 172 may be implemented with any of various spiralswithout deviating beyond the spirit and scope of the present disclosure.

FIGS. 6-7 illustrate an exemplary embodiment of a compression bone screw180 that may be used for repairing bones of a patient. The compressionbone screw 180 is substantially similar to the compression bone screw100, illustrated in FIGS. 1-3, with the exception that the compressionbone screw 180 is comprised of intermediate threads 184 in lieu of thesmooth portion 144. As best shown in FIG. 7, the intermediate threads184 extend from the distal threads 140 to the proximal threads 136, suchthat a continuous series of threads are disposed along substantially anentirety of the shank 108. Further, a tapered diameter 188 extends fromthe distal threads 140 to the distal end 116. The tapered diameter 188and the distal end 116 are configured to minimize resistance to forwardmovement of the compression bone screw 180 advancing within the interiorof a bone hole. It is contemplated that, in some embodiments, thetapered diameter 188 may be further comprised of one or more flutes 172and cutting edges 176 that extend from the distal end 116 to the distalthreads 140, as described herein.

The intermediate threads 184 may have a thread pitch that generallychanges along the length of the shank 108. In the illustrated embodimentof FIGS. 6-7, the intermediate threads 184 have a thread pitch thatcontinuously decreases from the thread pitch of the distal threads 140to the relatively smaller thread pitch of the proximal threads 136. Insome embodiments, the intermediate threads 184 may be comprised of athread pitch near the distal threads 140 that ranges betweensubstantially 1-3 times greater than the thread pitch of theintermediate threads that are near the proximal threads 136. In someembodiments, the intermediate threads 184 may be comprised of a threadpitch near the distal threads 140 that decreases from substantially2-times greater than the thread pitch near the proximal threads 136.During operation of the compression bone screw 180, the greater threadpitch of the distal threads 140 and nearby intermediate threads 184pushes the bone portion near the distal threads toward the bone portionnear the proximal threads 136. As will be appreciated, during operationof the compression bone screw 180, the decreasing thread pitch of theintermediate threads 184 contributes to compressing the bone portionnear the distal threads 140 toward the bone portion near the proximalthreads 136. A wide variety of differential pitch configurations arecontemplated within the scope of the present disclosure.

Moreover, in some embodiments, wherein the proximal threads 136 have alarger diameter than the distal threads 140, the intermediate threads184 may be comprised of a diameter that continuously increases from thediameter of the distal threads 140 to the diameter of the proximalthreads 136. In some embodiments, the intermediate threads 184 may havea diameter that is larger than the diameter of the distal threads 140and is smaller than the diameter of the proximal threads 136. In stillsome embodiments, the diameter of the intermediate threads 184 may besubstantially the same as the diameter of the distal threads 140 along amajority of the intermediate threads and then abruptly increase to matchthe diameter of the proximal threads 136. It should be understood,therefore, that a wide variety of relationships between the shapes andsizes of the distal threads 140, the intermediate threads 184, and theproximal threads 136 are contemplate and may be implemented within thespirit and the scope of the present disclosure.

While the invention has been described in terms of particular variationsand illustrative figures, those of ordinary skill in the art willrecognize that the invention is not limited to the variations or figuresdescribed. In addition, where methods and steps described above indicatecertain events occurring in certain order, those of ordinary skill inthe art will recognize that the ordering of certain steps may bemodified and that such modifications are in accordance with thevariations of the invention. Additionally, certain of the steps may beperformed concurrently in a parallel process when possible, as well asperformed sequentially as described above. To the extent there arevariations of the invention, which are within the spirit of thedisclosure or equivalent to the inventions found in the claims, it isthe intent that this patent will cover those variations as well.Therefore, the present disclosure is to be understood as not limited bythe specific embodiments described herein, but only by scope of theappended claims.

1.-20. (canceled)
 21. A bone compression screw, comprising: a shank and a head portion; a center hole extending through the head portion and the shank; and threads disposed along the shank.
 22. The bone compression screw of claim 21, wherein the threads include at least distal threads near a distal end of the shank and proximal threads near the head portion.
 23. The bone compression screw of claim 22, wherein the threads include a differential pitch comprising a distal thread pitch that is greater than a proximal thread pitch.
 24. The bone compression screw of claim 23, wherein the distal thread pitch ranges between substantially 1 to 3 times greater than the proximal thread pitch.
 25. The bone compression screw of claim 24, wherein the distal thread pitch is substantially 2 times greater than the proximal thread pitch.
 26. The bone compression screw of claim 23, wherein the distal thread pitch is configured to push a distal bone portion toward a proximal bone portion.
 27. The bone compression screw of claim 26, wherein a smooth portion is disposed between the distal threads and the proximal threads to allow the distal bone portion and the proximal bone portion to be compressed together.
 28. The bone compression screw of claim 23, wherein the differential pitch is adapted for compressing bone fractures, fixating osteotomies, and joining fusions.
 29. The bone compression screw of claim 22, wherein the threads include intermediate threads disposed between the distal threads and the proximal threads.
 30. The bone compression screw of claim 29, wherein the intermediate threads extend from the distal threads to the proximal threads, such that a continuous series of threads is disposed along substantially an entirety of the shank.
 31. The bone compression screw of claim 30, wherein the intermediate threads include an intermediate thread pitch that changes along the length of the shank.
 32. The bone compression screw of claim 31, wherein the intermediate thread pitch increases from the proximal thread pitch to the distal thread pitch.
 33. The bone compression screw of claim 32, wherein the intermediate thread pitch increases from a first thread pitch that is substantially the same as the proximal thread pitch to a second thread pitch that ranges between substantially 1 to 3 times greater than the proximal thread pitch.
 34. The bone compression screw of claim 33, wherein the second thread pitch is about 2 times greater than the first thread pitch.
 35. The bone compression screw of claim 32, wherein the first thread pitch and the second thread pitch cause the intermediate threads to contribute to compressing a distal bone portion against a proximal bone portion.
 36. The bone compression screw of claim 22, wherein the shank includes a tapered diameter between the distal threads and the distal end of the shank.
 37. The bone compression screw of claim 36, wherein the tapered diameter and the distal end are adapted to minimize resistance to forward movement of the compression bone screw within a hole drilled in bone.
 38. The bone compression screw of claim 36, wherein the tapered diameter includes one or more flutes and cutting edges that extend from the center hole to the distal threads.
 39. The bone compression screw of claim 38, wherein a pair of cutting edges borders each of the one or more flutes.
 40. The bone compression screw of claim 39, wherein the tapered diameter includes three flutes and six cutting edges. 